By Mike Baker BBC education correspondent

Electoral politics should be about choice.

The Conservatives' decision to abolish university tuition fees means voters now have a genuinely varied menu of higher education policies to select from.

There will be many choices: further expansion of universities or a halt to growth; higher fees for students or no fees at all; more young people taking degrees or more going into sub-degree vocational courses.

There is a genuine debate to be had on all these issues. Yet we enter it with the two main political parties having apparently swapped roles.

Labour, the old opponent of the fee-paying school sector, is now the party which ended the long-standing principle of free higher education.

It wants to entrust future growth to the market, with universities free to set their own fee levels up to a maximum of �3,000 a year.

'Uncertainties'

The Conservatives, who have long upheld the right of independent schools to charge fees, want to remove that freedom from universities.

They also want to reduce the market principle by re-establishing another, namely free university tuition.

Yet there are great uncertainties about both their plans - and about the Liberal Democrats, who are important players in this debate, as they have shown by changing student fee arrangements in Scotland.

Perhaps the greatest uncertainty is over just how many young people should be going to university.

The government's target is 50% by 2010. This does not mean, as many assume, half of all school-leavers.

The target is less ambitious than that. It is for half of all people to have experienced some form of higher education by the age of 30.

The Conservatives say that is too many. They believe there are too many worthless courses and, although they won't name them, they cite the comments about 'Mickey Mouse courses' made by the Education Minister, Margaret Hodge.

Is Iain Duncan Smith taking over Labour's position?

The proportion of 18 to 30 year olds going to university in England is 43%.

That is where the Conservatives want to keep it. But what is so special about 43%?

Some might argue it should be lower, others that it should be higher. But we need to know their arguments.

Just as Labour's 50% figure seemed somewhat arbitrary, why do the Tories think 43% is just about right?

After all, in Scotland it is already 50%. Does Labour want no further expansion north of the border? Do the Tories think student numbers in Scotland should be cut?

And what sort of courses should students be taking? The Education Secretary, Charles Clarke, has questioned public funding of purely academic courses.

However, ministers have been clear they do not want expansion to mean "more of the same".

Where to study?

Instead of more middle-class students reading philosophy at the older universities, they want students taking two-year foundation degrees in vocational subjects, such as aircraft engineering.

Hang on a minute, though. Isn't that more or less what the Conservatives want too?

Their spokesman, Damian Green, says he wants "more decent vocational courses".

Perhaps, then, the difference between them is not so much what students study, but where they do it?

The Tories are calling for better vocational education

The Conservatives might argue that university campuses are not the best place to study practical, job-related courses.

Setting aside the awkward anomaly of "vocational" subjects like law and medicine, they may have a point.

Perhaps we should be directing more students towards their local further education colleges, rather than to universities?

But, just a second, where are these foundation degrees and vocational courses being offered now?

In fact, more than 11% of higher education courses are already provided at local FE colleges.

I attended a recent conference on the new foundation degrees.

Most of the delegates were from FE Colleges and those representing universities were talking not of running foundation degrees on their own, but of partnerships with FE.

In the end, students will study whatever suits them, wherever it suits them.

Market of sorts

Employers will shape that demand by their patterns of recruitment.

If thousands of media studies graduates cannot find a job, then the numbers on such courses will decline (in fact, Media Studies graduates have one of the better rates of employment).

Students I spoke to on an aeronautical engineering foundation degree knew just why they were doing it. It offered a simultaneous academic qualification and a job-related apprenticeship.

Equally, though, many big employers still want history graduates because they value their flexible, transferable skills in a fast-changing economy where employees constantly need to update their role.

It is the job of politicians to try to shape the future. But higher education, while it can be nudged this way or that, still remains a market of sorts.

Politicians cannot easily control either the extent or direction of change.

Universities grew like Topsy under the Conservatives in the 1980s because the Education Secretary, Kenneth Baker, opened the door to market forces.

Once he had changed the funding arrangements to follow student demand, the numbers sky-rocketed. The government had little control over the direction or extent of growth.

Similarly, Labour's expansion plans could be reversed if students decide that higher fees erode the economic return of investing in a university degree.

Equally, the Conservatives' plans could go awry if the growing numbers of young people getting good A-level grades refuse to have their path to university blocked.